The steroid hormone estrogen (E) acting via the estrogen receptor (ER) has many physiological actions, including mediating regulatory events in the neuroendocrine system that govern pituitary cell function and hormone secretion. Estrogen acts on the pituitary to regulate hormone secretion and gene expression. Our lab has identified and characterized a pituitary-specific truncated form of estrogen receptor-alpha (TERP). TERP is dramatically regulated by E, and has stimulatory or suppressive effects on ER activity, dependent on its levels of expression relative to full-length ER. We have cloned the intronic TERP promoter, and propose to characterize its basal activity and E responsiveness in transient transfection assays with TERP-luciferase deletion/mutation constructs. We will also determine if TERP regulates its own promoter by modulating its response to E.